25.1 INTRODUCTION

Flyblades are used for generation of worm-gears in small-scale production to avoid the manufacture of expensive hobs. However, the production of worm-gears by flyblades is less effective in comparison with production by hobs. The profiles of the flyblades are determined as profiles of the worm thread in the normal tooth section obtained by intersection of the thread by plane ? (Fig. 25.1.1). The orientation of the plane ? is determined with the lead angle ? _p on the worm pitch cylinder.

A symmetrical location of the profiles of the flyblade in coordinate system can be obtained if the axis is the axis of symmetry of the worm thread. In Chapter 19, we have derived equations of worm surfaces for the case when the x ₁ axis of coordinate system S ₁ is the axis of symmetry of the worm space. To obtain the desired location of axis x ₁ (as the axis of tooth symmetry), it is necessary to displace the origin O ₁ of coordinate system S ₁ in the axial direction at the magnitude a _o = p _ax /2, where p _ax is the axial distance between two neighboring threads of the worm.

The process of generation of the worm-gear by a flyblade simulates the meshing of the worm with the worm-gear in such a specific case when the worm performs translational motion in an axial direction in addition to...